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Developmental changes in regulation of embryonic chick heart gap junctions
1Department of Pharmacology, State University of New York/Health Science Center, Syracuse 13210.
The Journal of Membrane Biology
|February 1, 1991
Summary
Cardiac development alters intercellular communication. Gap junction conductance regulation changes, with voltage sensitivity increasing and basal conductance doubling between embryonic days 4 and 18.
Area of Science:
- Cardiovascular Biology
- Developmental Biology
- Cellular Electrophysiology
Background:
- Intercellular communication via gap junctions is crucial for cardiac function.
- Understanding developmental changes in gap junction regulation is key to comprehending heart development.
Purpose of the Study:
- To investigate the relationship between junctional conductance and transjunctional voltage during cardiac development.
- To quantify changes in gap junction properties in embryonic chick myocytes from day 4 to day 18.
Main Methods:
- Isolation of embryonic chick myocyte pairs from ventricular tissue.
- Utilizing the double whole-cell patch-clamp technique to measure junctional conductance.
- Analyzing conductance-voltage relationships and fitting data to a Boltzmann distribution model.
Main Results:
- Junctional conductance showed a linear initial response to transjunctional voltage, followed by voltage- and time-dependent inactivation.
- Half-inactivation voltage shifted by 10 mV, gating charge increased by ~1 electron, and minimal conductance doubled (18% to 36%) during development.
- Decay time constants were similar across ages, increasing with transjunctional potential.
Conclusions:
- Direct experimental evidence demonstrates developmental regulation of intercellular communication in cardiac tissue.
- Changes in gap junction properties suggest developmental expression of multiple connexins with distinct regulatory mechanisms.